The Dampier to Bunbury Natural Gas Pipeline (DBNGP) is one of the largest capacity natural gas pipelines in Australia supplying natural gas to industrial, commercial and residential customers in Perth and major regional centres along the pipeline route.

Gas contributes up to 50 per cent of Western Australia’s primary energy use and fuels up 60 per cent of the state’s electricity generation capacity. The DBNGP is the only natural gas pipeline connecting the Carnarvon Basin on Western Australia’s North West Shelf with Perth and the surrounding region.

It comes as no surprise then that pipeline owner Dampier Bunbury Pipeline (DBP) has expanded the pipeline’s capacity twice since it, acquired the pipeline in 2004 and has recently obtained necessary financing and equity commitments for an additional expansion.

DBP bought the pipeline from Epic Energy in October 2004, which had previously purchased the pipeline from the state government in 1998. Since taking ownership, DBP has made expansion of the DBNGP a key focus of the company, committing a total of $1.8 billion to expanding the pipeline’s gas haulage capacity to meet Western Australia’s growing demand. This equates to 125 per cent of the regulated value of the pipeline as at 2005.

Expansions in the pipeline

In May 2005 the DBP board approved a $430 million expansion program – known as the Stage 4 Expansion – comprising eight new compressors and over 200 km of looping. Looping involves installing additional pipeline parallel to the existing pipeline and then connecting the new pipeline back into the existing pipeline. This expansion increased the pipeline’s capacity by over 100 terajoules per day (TJ/d) and was completed on time and within budget in February 2007.

Before the Stage 4 Expansion was complete, DBP announced a further expansion known as Stage 5, which includes an additional 1,150 km of new pipeline loops and the installation of one 7 megawatt (MW) and a further four 10MW compressors.

The first component, Stage 5A, commenced construction in late February 2007. It comprised 10 loops constructed by Saipem, with a total length of 570 km, adding approximately 90 TJ/d of full haul capacity to the DBNGP. A total of 700 people worked on the expansion, with 650 located on site. Major contractors for the project included Saipem and Enerflex for the construction of compressor stations. WorleyParsons provided engineering, design and project services personnel, OSD Pipelines provided key pipeline expertise and PCT supplied project regulation and engineering expertise.

All contractors adhered to a Zero Harm approach to safety and to the environment, which saw operations comply with, and often exceed, the requirements of all relevant regulations and standards.

DBP Executive Chairman Stuart Hohnen said “The Stage 5A expansion was delivered on time and on budget in a climate where many projects of this scale suffer delays and cost overruns.”

He added that completion of Stage 5A was a considerable achievement on the part of all concerned, including project manager WestNet Energy, a division of Alinta Asset Management.

The project also required major community and stakeholder consultation, with over 300 individuals or representative bodies engaged in the consultation process to ensure the project’s success. In total, the project required liaising with 280 landowners, 16 Shires, 3 Regional Divisions of Main Roads WA, 6 Regional Divisions of DPI, 10 other Government Departments, State Ministers and local members of parliament.

The pipeline’s proximity to homes, parks and playgrounds also meant a great deal of engineering analysis was required to ensure community safety.

The Stage 5A expansion also involved negotiating some key challenges. These included major river crossings – including the Robe, Yannarie, Minilya and the Murchison – dune crossings, and confirming that the pipeline route was safe for construction and trenching through historical military ranges. An investigation was conducted that confirmed over 60 km of pipeline easement was free of unexploded bombs and devices left over from 40-plus years of military target practice.

Increased capacity demand – what’s next for DBNGP?

The second Stage 5 component – Stage5B – will involve a further 440 km of looping and some additional compressor station modifications, with an estimated cost of $690 million. Construction is expected to commence early in 2009, with commissioning of the final tranche of the additional capacity due to occur in the second half of 2010.

Stage 5B represents further capacity requirements of approximately 110 TJ/d of firm full haul capacity and 140 TJ/d of part haul capacity in addition to the recently completed Stage 5A expansion.

DBP Executive Chairman Stuart Hohnen said that the decision to increase the Stage 5B expansion came after receiving additional firm capacity requests from existing and prospective shippers.

Benefits of looping

Following the recent pipeline rupture at Apache Energy’s Varanus Island facilities, cutting Western Australia’s gas supply by 30 per cent, there has been speculation about the need for a second major gas pipeline in the state.

However arguments against this take into account the production challenges Western Australia faces in regards to the supply of natural gas, as well as the ability for the DBNGP system to continue expanding through the progressive addition of further looping and compression.

The Stage 4 and 5 expansions will effectively duplicate approximately 90percent of the length of the DBNGP. DBP says that this is a much faster and more cost effective approach to the delivery of new capacity than the construction of a second pipeline system, which it says would be heavily underutilised for many years – at high cost to users.

The completed DBNGP expansion programs suggest that it is possible to engineer, finance and build new capacity in a shorter period of time than it takes to build new processing plants or power stations.

Mr Hohnen said “It could be said that the pipeline is the backbone of the booming Western Australia economy, the key to ongoing prosperity in this state. However we are functioning in a gas constrained environment and new supply is critical.”